The goal of the proposed research is to develop a dye-less, multi-reference wavelength NADH fluorimeter. The system, utilizing an inexpensive nitrogen laser as a pump, will use an optical parametric oscillator instead of a dye laser to generate the reference wavelength. The reference wavelength can be altered by simply pressing a button, instead of switching the dye as in the current NADH fluorimeter. The resulting system is more compact, less expensive, and more reliable than the current NADH fluorimeter. The ability to rapidly alter reference wavelengths could possibly be exploited in order to expand the application of NADH fluorimetry to areas where other artifacts may be present.